/*
 * Network proxy abstraction in PuTTY
 *
 * A proxy layer, if necessary, wedges itself between the network
 * code and the higher level backend.
 */

#include <assert.h>
#include <ctype.h>
#include <string.h>

#define DEFINE_PLUG_METHOD_MACROS
#include "putty.h"
#include "network.h"
#include "proxy.h"

#define do_proxy_dns(cfg) \
    (cfg->proxy_dns == FORCE_ON || \
	 (cfg->proxy_dns == AUTO && cfg->proxy_type != PROXY_SOCKS4))

/*
 * Call this when proxy negotiation is complete, so that this
 * socket can begin working normally.
 */
//void proxy_activate(Proxy_Socket p) {
//	void *data;
//	int len;
//	long output_before, output_after;
//
//	p->state = PROXY_STATE_ACTIVE;
//
//	/* we want to ignore new receive events until we have sent
//	 * all of our buffered receive data.
//	 */
//	sk_set_frozen(p->sub_socket, 1);
//
//	/* how many bytes of output have we buffered? */
//	output_before = bufchain_size(&p->pending_oob_output_data)
//			+ bufchain_size(&p->pending_output_data);
//	/* and keep track of how many bytes do not get sent. */
//	output_after = 0;
//
//	/* send buffered OOB writes */
//	while (bufchain_size(&p->pending_oob_output_data) > 0) {
//		bufchain_prefix(&p->pending_oob_output_data, &data, &len);
//		output_after += sk_write_oob(p->sub_socket, data, len);
//		bufchain_consume(&p->pending_oob_output_data, len);
//	}
//
//	/* send buffered normal writes */
//	while (bufchain_size(&p->pending_output_data) > 0) {
//		bufchain_prefix(&p->pending_output_data, &data, &len);
//		output_after += sk_write(p->sub_socket, data, len);
//		bufchain_consume(&p->pending_output_data, len);
//	}
//
//	/* if we managed to send any data, let the higher levels know. */
//	if (output_after < output_before)
//		plug_sent(p->plug, output_after);
//
//	/* if we were asked to flush the output during
//	 * the proxy negotiation process, do so now.
//	 */
//	if (p->pending_flush)
//		sk_flush(p->sub_socket);
//
//	/* if the backend wanted the socket unfrozen, try to unfreeze.
//	 * our set_frozen handler will flush buffered receive data before
//	 * unfreezing the actual underlying socket.
//	 */
//	if (!p->freeze)
//		sk_set_frozen((Socket)p, 0);
//}

/* basic proxy socket functions */

//static Plug sk_proxy_plug(Socket s, Plug p) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//	Plug ret = ps->plug;
//	if (p)
//		ps->plug = p;
//	return ret;
//}

//static void sk_proxy_close(Socket s) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//
//	sk_close(ps->sub_socket);
//	sk_addr_free(ps->remote_addr);
//	sfree(ps);
//}

//static int sk_proxy_write(Socket s, const char *data, int len) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//
//	if (ps->state != PROXY_STATE_ACTIVE) {
//		bufchain_add(&ps->pending_output_data, data, len);
//		return bufchain_size(&ps->pending_output_data);
//	}
//	return sk_write(ps->sub_socket, data, len);
//}

//static int sk_proxy_write_oob(Socket s, const char *data, int len) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//
//	if (ps->state != PROXY_STATE_ACTIVE) {
//		bufchain_clear(&ps->pending_output_data);
//		bufchain_clear(&ps->pending_oob_output_data);
//		bufchain_add(&ps->pending_oob_output_data, data, len);
//		return len;
//	}
//	return sk_write_oob(ps->sub_socket, data, len);
//}

//static void sk_proxy_flush(Socket s) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//
//	if (ps->state != PROXY_STATE_ACTIVE) {
//		ps->pending_flush = 1;
//		return;
//	}
//	sk_flush(ps->sub_socket);
//}

//static void sk_proxy_set_private_ptr(Socket s, void *ptr) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//	sk_set_private_ptr(ps->sub_socket, ptr);
//}

//static void * sk_proxy_get_private_ptr(Socket s) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//	return sk_get_private_ptr(ps->sub_socket);
//}

//static void sk_proxy_set_frozen(Socket s, int is_frozen) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//
//	if (ps->state != PROXY_STATE_ACTIVE) {
//		ps->freeze = is_frozen;
//		return;
//	}
//
//	/* handle any remaining buffered recv data first */
//	if (bufchain_size(&ps->pending_input_data) > 0) {
//		ps->freeze = is_frozen;
//
//		/* loop while we still have buffered data, and while we are
//		 * unfrozen. the plug_receive call in the loop could result
//		 * in a call back into this function refreezing the socket,
//		 * so we have to check each time.
//		 */
//		while (!ps->freeze && bufchain_size(&ps->pending_input_data) > 0) {
//			void *data;
//			char databuf[512];
//			int len;
//			bufchain_prefix(&ps->pending_input_data, &data, &len);
//			if (len > lenof(databuf))
//				len = lenof(databuf);
//			memcpy(databuf, data, len);
//			bufchain_consume(&ps->pending_input_data, len);
//			plug_receive(ps->plug, 0, databuf, len);
//		}
//
//		/* if we're still frozen, we'll have to wait for another
//		 * call from the backend to finish unbuffering the data.
//		 */
//		if (ps->freeze)
//			return;
//	}
//
//	sk_set_frozen(ps->sub_socket, is_frozen);
//}

//static const char * sk_proxy_socket_error(Socket s) {
//	Proxy_Socket ps = (Proxy_Socket) s;
//	if (ps->error != NULL || ps->sub_socket == NULL) {
//		return ps->error;
//	}
//	return sk_socket_error(ps->sub_socket);
//}

/* basic proxy plug functions */

//static void plug_proxy_log(Plug plug, int type, SockAddr addr, int port,
//		const char *error_msg, int error_code) {
//	Proxy_Plug pp = (Proxy_Plug) plug;
//	Proxy_Socket ps = pp->proxy_socket;
//
//	plug_log(ps->plug, type, addr, port, error_msg, error_code);
//}

//static int plug_proxy_closing(Plug p, const char *error_msg, int error_code,
//		int calling_back) {
//	Proxy_Plug pp = (Proxy_Plug) p;
//	Proxy_Socket ps = pp->proxy_socket;
//
//	if (ps->state != PROXY_STATE_ACTIVE) {
//		ps->closing_error_msg = error_msg;
//		ps->closing_error_code = error_code;
//		ps->closing_calling_back = calling_back;
//		return ps->negotiate(ps, PROXY_CHANGE_CLOSING);
//	}
//	return plug_closing(ps->plug, error_msg, error_code, calling_back);
//}

//static int plug_proxy_receive(Plug p, int urgent, char *data, int len) {
//	Proxy_Plug pp = (Proxy_Plug) p;
//	Proxy_Socket ps = pp->proxy_socket;
//
//	if (ps->state != PROXY_STATE_ACTIVE) {
//		/* we will lose the urgentness of this data, but since most,
//		 * if not all, of this data will be consumed by the negotiation
//		 * process, hopefully it won't affect the protocol above us
//		 */
//		bufchain_add(&ps->pending_input_data, data, len);
//		ps->receive_urgent = urgent;
//		ps->receive_data = data;
//		ps->receive_len = len;
//		return ps->negotiate(ps, PROXY_CHANGE_RECEIVE);
//	}
//	return plug_receive(ps->plug, urgent, data, len);
//}

//static void plug_proxy_sent(Plug p, int bufsize) {
//	Proxy_Plug pp = (Proxy_Plug) p;
//	Proxy_Socket ps = pp->proxy_socket;
//
//	if (ps->state != PROXY_STATE_ACTIVE) {
//		ps->sent_bufsize = bufsize;
//		ps->negotiate(ps, PROXY_CHANGE_SENT);
//		return;
//	}
//	plug_sent(ps->plug, bufsize);
//}

//static int plug_proxy_accepting(Plug p, OSSocket sock) {
//	Proxy_Plug pp = (Proxy_Plug) p;
//	Proxy_Socket ps = pp->proxy_socket;
//
//	if (ps->state != PROXY_STATE_ACTIVE) {
//		ps->accepting_sock = sock;
//		return ps->negotiate(ps, PROXY_CHANGE_ACCEPTING);
//	}
//	return plug_accepting(ps->plug, sock);
//}

/*
 * This function can accept a NULL pointer as `addr', in which case
 * it will only check the host name.
 */
//static int proxy_for_destination(SockAddr addr, char *hostname, int port,
//		const Config *cfg) {
//	int s = 0, e = 0;
//	char hostip[64];
//	int hostip_len, hostname_len;
//	const char *exclude_list;
//
//	/*
//	 * Check the host name and IP against the hard-coded
//	 * representations of `localhost'.
//	 */
//	if (!cfg->even_proxy_localhost
//			&& (sk_hostname_is_local(hostname)
//					|| (addr && sk_address_is_local(addr))))
//		return 0; /* do not proxy */
//
//	/* we want a string representation of the IP address for comparisons */
//	if (addr) {
//		sk_getaddr(addr, hostip, 64);
//		hostip_len = strlen(hostip);
//	} else
//		hostip_len = 0; /* placate gcc; shouldn't be required */
//
//	hostname_len = strlen(hostname);
//
//	exclude_list = cfg->proxy_exclude_list;
//
//	/* now parse the exclude list, and see if either our IP
//	 * or hostname matches anything in it.
//	 */
//
//	while (exclude_list[s]) {
//		while (exclude_list[s]
//				&& (isspace((unsigned char) exclude_list[s])
//						|| exclude_list[s] == ','))
//			s++;
//
//		if (!exclude_list[s])
//			break;
//
//		e = s;
//
//		while (exclude_list[e]
//				&& (isalnum((unsigned char) exclude_list[e])
//						|| exclude_list[e] == '-' || exclude_list[e] == '.'
//						|| exclude_list[e] == '*'))
//			e++;
//
//		if (exclude_list[s] == '*') {
//			/* wildcard at beginning of entry */
//
//			if ((addr
//					&& strnicmp(hostip + hostip_len - (e - s - 1),
//							exclude_list + s + 1, e - s - 1) == 0)
//					|| strnicmp(hostname + hostname_len - (e - s - 1),
//							exclude_list + s + 1, e - s - 1) == 0)
//				return 0; /* IP/hostname range excluded. do not use proxy. */
//
//		} else if (exclude_list[e - 1] == '*') {
//			/* wildcard at end of entry */
//
//			if ((addr && strnicmp(hostip, exclude_list + s, e - s - 1) == 0)
//					|| strnicmp(hostname, exclude_list + s, e - s - 1) == 0)
//				return 0; /* IP/hostname range excluded. do not use proxy. */
//
//		} else {
//			/* no wildcard at either end, so let's try an absolute
//			 * match (ie. a specific IP)
//			 */
//
//			if (addr && strnicmp(hostip, exclude_list + s, e - s) == 0)
//				return 0; /* IP/hostname excluded. do not use proxy. */
//			if (strnicmp(hostname, exclude_list + s, e - s) == 0)
//				return 0; /* IP/hostname excluded. do not use proxy. */
//		}
//
//		s = e;
//
//		/* Make sure we really have reached the next comma or end-of-string */
//		while (exclude_list[s] && !isspace((unsigned char) exclude_list[s])
//				&& exclude_list[s] != ',')
//			s++;
//	}
//
//	/* no matches in the exclude list, so use the proxy */
//	return 1;
//}

SockAddr name_lookup(char *host, int port, char **canonicalname,
                     const Config *cfg, int addressfamily)
{
    //	if (cfg->proxy_type != PROXY_NONE && do_proxy_dns(cfg)
    //			&& proxy_for_destination(NULL, host, port, cfg)) {
    //		*canonicalname = dupstr(host);
    //		return sk_nonamelookup(host);
    //	}

    return sk_namelookup(host, canonicalname, addressfamily);
}

Socket new_connection(SockAddr addr, char *hostname, int port, int privport,
                      int oobinline, int nodelay, int keepalive, Plug plug, const Config *cfg)
{
    //	static const struct socket_function_table socket_fn_table = { sk_proxy_plug,
    //			sk_proxy_close, sk_proxy_write, sk_proxy_write_oob, sk_proxy_flush,
    //			sk_proxy_set_private_ptr, sk_proxy_get_private_ptr,
    //			sk_proxy_set_frozen, sk_proxy_socket_error };

    //	static const struct plug_function_table plug_fn_table = { plug_proxy_log,
    //			plug_proxy_closing, plug_proxy_receive, plug_proxy_sent,
    //			plug_proxy_accepting };

    //	if (cfg->proxy_type != PROXY_NONE
    //			&& proxy_for_destination(addr, hostname, port, cfg)) {
    //		Proxy_Socket ret;
    //		Proxy_Plug pplug;
    //		SockAddr proxy_addr;
    //		char *proxy_canonical_name;
    //		Socket sret;
    //
    //		if ((sret = platform_new_connection(addr, hostname, port, privport,
    //				oobinline, nodelay, keepalive, plug, cfg)) != NULL)
    //			return sret;
    //
    //		ret = snew(struct Socket_proxy_tag);
    //		ret->fn = &socket_fn_table;
    //		ret->cfg = *cfg; /* STRUCTURE COPY */
    //		ret->plug = plug;
    //		ret->remote_addr = addr; /* will need to be freed on close */
    //		ret->remote_port = port;
    //
    //		ret->error = NULL;
    //		ret->pending_flush = 0;
    //		ret->freeze = 0;
    //
    //		bufchain_init(&ret->pending_input_data);
    //		bufchain_init(&ret->pending_output_data);
    //		bufchain_init(&ret->pending_oob_output_data);
    //
    //		ret->sub_socket = NULL;
    //		ret->state = PROXY_STATE_NEW;
    //		ret->negotiate = NULL;
    //
    //		if (cfg->proxy_type == PROXY_HTTP) {
    //			ret->negotiate = proxy_http_negotiate;
    //		} else if (cfg->proxy_type == PROXY_SOCKS4) {
    //			ret->negotiate = proxy_socks4_negotiate;
    //		} else if (cfg->proxy_type == PROXY_SOCKS5) {
    //			ret->negotiate = proxy_socks5_negotiate;
    //		} else if (cfg->proxy_type == PROXY_TELNET) {
    //			ret->negotiate = proxy_telnet_negotiate;
    //		} else {
    //			ret->error = "Proxy error: Unknown proxy method";
    //			return (Socket) ret;
    //		}
    //
    //		/* create the proxy plug to map calls from the actual
    //		 * socket into our proxy socket layer */
    //		pplug = snew(struct Plug_proxy_tag);
    //		pplug->fn = &plug_fn_table;
    //		pplug->proxy_socket = ret;
    //
    //		/* look-up proxy */
    //		proxy_addr = sk_namelookup(cfg->proxy_host, &proxy_canonical_name,
    //				cfg->addressfamily);
    //		if (sk_addr_error(proxy_addr) != NULL) {
    //			ret->error = "Proxy error: Unable to resolve proxy host name";
    //			return (Socket) ret;
    //		}
    //		sfree(proxy_canonical_name);
    //
    //		/* create the actual socket we will be using,
    //		 * connected to our proxy server and port.
    //		 */
    //		ret->sub_socket = sk_new(proxy_addr, cfg->proxy_port, privport,
    //				oobinline, nodelay, keepalive, (Plug) pplug);
    //		if (sk_socket_error(ret->sub_socket) != NULL)
    //			return (Socket) ret;
    //
    //		/* start the proxy negotiation process... */
    //		sk_set_frozen(ret->sub_socket, 0);
    //		ret->negotiate(ret, PROXY_CHANGE_NEW);
    //
    //		return (Socket) ret;
    //	}

    /* no proxy, so just return the direct socket */
    return sk_new(addr, port, privport, oobinline, nodelay, keepalive, plug);
}

Socket new_listener(char *srcaddr, int port, Plug plug, int local_host_only,
                    const Config *cfg, int addressfamily)
{
    /* TODO: SOCKS (and potentially others) support inbound
     * TODO: connections via the proxy. support them.
     */

    return sk_newlistener(srcaddr, port, plug, local_host_only, addressfamily);
}

/* ----------------------------------------------------------------------
 * HTTP CONNECT proxy type.
 */

//static int get_line_end(char * data, int len) {
//	int off = 0;
//
//	while (off < len) {
//		if (data[off] == '\n') {
//			/* we have a newline */
//			off++;
//
//			/* is that the only thing on this line? */
//			if (off <= 2)
//				return off;
//
//			/* if not, then there is the possibility that this header
//			 * continues onto the next line, if it starts with a space
//			 * or a tab.
//			 */
//
//			if (off + 1 < len && data[off + 1] != ' ' && data[off + 1] != '\t')
//				return off;
//
//			/* the line does continue, so we have to keep going
//			 * until we see an the header's "real" end of line.
//			 */
//			off++;
//		}
//
//		off++;
//	}
//
//	return -1;
//}

//int proxy_http_negotiate(Proxy_Socket p, int change) {
//	if (p->state == PROXY_STATE_NEW) {
//		/* we are just beginning the proxy negotiate process,
//		 * so we'll send off the initial bits of the request.
//		 * for this proxy method, it's just a simple HTTP
//		 * request
//		 */
//		char *buf, dest[512];
//
//		sk_getaddr(p->remote_addr, dest, lenof(dest));
//
//		buf = dupprintf("CONNECT %s:%i HTTP/1.1\r\nHost: %s:%i\r\n", dest,
//				p->remote_port, dest, p->remote_port);
//		sk_write(p->sub_socket, buf, strlen(buf));
//		sfree(buf);
//
//		if (p->cfg.proxy_username[0] || p->cfg.proxy_password[0]) {
//			char buf[sizeof(p->cfg.proxy_username)
//					+ sizeof(p->cfg.proxy_password)];
//			char buf2[sizeof(buf) * 4 / 3 + 100];
//			int i, j, len;
//			sprintf(buf, "%s:%s", p->cfg.proxy_username, p->cfg.proxy_password);
//			len = strlen(buf);
//			sprintf(buf2, "Proxy-Authorization: Basic ");
//			for (i = 0, j = strlen(buf2); i < len; i += 3, j += 4)
//				base64_encode_atom((unsigned char *) (buf + i),
//						(len - i > 3 ? 3 : len - i), buf2 + j);
//			strcpy(buf2 + j, "\r\n");
//			sk_write(p->sub_socket, buf2, strlen(buf2));
//		}
//
//		sk_write(p->sub_socket, "\r\n", 2);
//
//		p->state = 1;
//		return 0;
//	}
//
//	if (change == PROXY_CHANGE_CLOSING) {
//		/* if our proxy negotiation process involves closing and opening
//		 * new sockets, then we would want to intercept this closing
//		 * callback when we were expecting it. if we aren't anticipating
//		 * a socket close, then some error must have occurred. we'll
//		 * just pass those errors up to the backend.
//		 */
//		return plug_closing(p->plug, p->closing_error_msg,
//				p->closing_error_code, p->closing_calling_back);
//	}
//
//	if (change == PROXY_CHANGE_SENT) {
//		/* some (or all) of what we wrote to the proxy was sent.
//		 * we don't do anything new, however, until we receive the
//		 * proxy's response. we might want to set a timer so we can
//		 * timeout the proxy negotiation after a while...
//		 */
//		return 0;
//	}
//
//	if (change == PROXY_CHANGE_ACCEPTING) {
//		/* we should _never_ see this, as we are using our socket to
//		 * connect to a proxy, not accepting inbound connections.
//		 * what should we do? close the socket with an appropriate
//		 * error message?
//		 */
//		return plug_accepting(p->plug, p->accepting_sock);
//	}
//
//	if (change == PROXY_CHANGE_RECEIVE) {
//		/* we have received data from the underlying socket, which
//		 * we'll need to parse, process, and respond to appropriately.
//		 */
//
//		char *data, *datap;
//		int len;
//		int eol;
//
//		if (p->state == 1) {
//
//			int min_ver, maj_ver, status;
//
//			/* get the status line */
//			len = bufchain_size(&p->pending_input_data);
//			assert(len > 0);
//			/* or we wouldn't be here */
//			data = snewn(len+1, char);
//			bufchain_fetch(&p->pending_input_data, data, len);
//			/*
//			 * We must NUL-terminate this data, because Windows
//			 * sscanf appears to require a NUL at the end of the
//			 * string because it strlens it _first_. Sigh.
//			 */
//			data[len] = '\0';
//
//			eol = get_line_end(data, len);
//			if (eol < 0) {
//				sfree(data);
//				return 1;
//			}
//
//			status = -1;
//			/* We can't rely on whether the %n incremented the sscanf return */
//			if (sscanf((char *) data, "HTTP/%i.%i %n", &maj_ver, &min_ver,
//					&status) < 2 || status == -1) {
//				plug_closing(p->plug, "Proxy error: HTTP response was absent",
//						PROXY_ERROR_GENERAL, 0);
//				sfree(data);
//				return 1;
//			}
//
//			/* remove the status line from the input buffer. */
//			bufchain_consume(&p->pending_input_data, eol);
//			if (data[status] != '2') {
//				/* error */
//				char *buf;
//				data[eol] = '\0';
//				while (eol > status
//						&& (data[eol - 1] == '\r' || data[eol - 1] == '\n'))
//					data[--eol] = '\0';
//				buf = dupprintf("Proxy error: %s", data + status);
//				plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
//				sfree(buf);
//				sfree(data);
//				return 1;
//			}
//
//			sfree(data);
//
//			p->state = 2;
//		}
//
//		if (p->state == 2) {
//
//			/* get headers. we're done when we get a
//			 * header of length 2, (ie. just "\r\n")
//			 */
//
//			len = bufchain_size(&p->pending_input_data);
//			assert(len > 0);
//			/* or we wouldn't be here */
//			data = snewn(len, char);
//			datap = data;
//			bufchain_fetch(&p->pending_input_data, data, len);
//
//			eol = get_line_end(datap, len);
//			if (eol < 0) {
//				sfree(data);
//				return 1;
//			}
//			while (eol > 2) {
//				bufchain_consume(&p->pending_input_data, eol);
//				datap += eol;
//				len -= eol;
//				eol = get_line_end(datap, len);
//			}
//
//			if (eol == 2) {
//				/* we're done */
//				bufchain_consume(&p->pending_input_data, 2);
//				proxy_activate(p);
//				/* proxy activate will have dealt with
//				 * whatever is left of the buffer */sfree(data);
//				return 1;
//			}
//
//			sfree(data);
//			return 1;
//		}
//	}
//
//	plug_closing(p->plug, "Proxy error: unexpected proxy error",
//			PROXY_ERROR_UNEXPECTED, 0);
//	return 1;
//}

/* ----------------------------------------------------------------------
 * SOCKS proxy type.
 */

/* SOCKS version 4 */
//int proxy_socks4_negotiate(Proxy_Socket p, int change) {
//	if (p->state == PROXY_CHANGE_NEW) {
//
//		/* request format:
//		 *  version number (1 byte) = 4
//		 *  command code (1 byte)
//		 *    1 = CONNECT
//		 *    2 = BIND
//		 *  dest. port (2 bytes) [network order]
//		 *  dest. address (4 bytes)
//		 *  user ID (variable length, null terminated string)
//		 */
//
//		int length, type, namelen;
//		char *command, addr[4], hostname[512];
//
//		type = sk_addrtype(p->remote_addr);
//		if (type == ADDRTYPE_IPV6) {
//			plug_closing(p->plug, "Proxy error: SOCKS version 4 does"
//					" not support IPv6", PROXY_ERROR_GENERAL, 0);
//			return 1;
//		} else if (type == ADDRTYPE_IPV4) {
//			namelen = 0;
//			sk_addrcopy(p->remote_addr, addr);
//		} else { /* type == ADDRTYPE_NAME */
//			assert(type == ADDRTYPE_NAME);
//			sk_getaddr(p->remote_addr, hostname, lenof(hostname));
//			namelen = strlen(hostname) + 1; /* include the NUL */
//			addr[0] = addr[1] = addr[2] = 0;
//			addr[3] = 1;
//		}
//
//		length = strlen(p->cfg.proxy_username) + namelen + 9;
//		command = snewn(length, char);
//		strcpy(command + 8, p->cfg.proxy_username);
//
//		command[0] = 4; /* version 4 */
//		command[1] = 1; /* CONNECT command */
//
//		/* port */
//		command[2] = (char) (p->remote_port >> 8) & 0xff;
//		command[3] = (char) p->remote_port & 0xff;
//
//		/* address */
//		memcpy(command + 4, addr, 4);
//
//		/* hostname */
//		memcpy(command + 8 + strlen(p->cfg.proxy_username) + 1, hostname,
//				namelen);
//
//		sk_write(p->sub_socket, command, length);
//		sfree(command);
//
//		p->state = 1;
//		return 0;
//	}
//
//	if (change == PROXY_CHANGE_CLOSING) {
//		/* if our proxy negotiation process involves closing and opening
//		 * new sockets, then we would want to intercept this closing
//		 * callback when we were expecting it. if we aren't anticipating
//		 * a socket close, then some error must have occurred. we'll
//		 * just pass those errors up to the backend.
//		 */
//		return plug_closing(p->plug, p->closing_error_msg,
//				p->closing_error_code, p->closing_calling_back);
//	}
//
//	if (change == PROXY_CHANGE_SENT) {
//		/* some (or all) of what we wrote to the proxy was sent.
//		 * we don't do anything new, however, until we receive the
//		 * proxy's response. we might want to set a timer so we can
//		 * timeout the proxy negotiation after a while...
//		 */
//		return 0;
//	}
//
//	if (change == PROXY_CHANGE_ACCEPTING) {
//		/* we should _never_ see this, as we are using our socket to
//		 * connect to a proxy, not accepting inbound connections.
//		 * what should we do? close the socket with an appropriate
//		 * error message?
//		 */
//		return plug_accepting(p->plug, p->accepting_sock);
//	}
//
//	if (change == PROXY_CHANGE_RECEIVE) {
//		/* we have received data from the underlying socket, which
//		 * we'll need to parse, process, and respond to appropriately.
//		 */
//
//		if (p->state == 1) {
//			/* response format:
//			 *  version number (1 byte) = 4
//			 *  reply code (1 byte)
//			 *    90 = request granted
//			 *    91 = request rejected or failed
//			 *    92 = request rejected due to lack of IDENTD on client
//			 *    93 = request rejected due to difference in user ID
//			 *         (what we sent vs. what IDENTD said)
//			 *  dest. port (2 bytes)
//			 *  dest. address (4 bytes)
//			 */
//
//			char data[8];
//
//			if (bufchain_size(&p->pending_input_data) < 8)
//				return 1; /* not got anything yet */
//
//			/* get the response */
//			bufchain_fetch(&p->pending_input_data, data, 8);
//
//			if (data[0] != 0) {
//				plug_closing(p->plug, "Proxy error: SOCKS proxy responded with "
//						"unexpected reply code version", PROXY_ERROR_GENERAL,
//						0);
//				return 1;
//			}
//
//			if (data[1] != 90) {
//
//				switch (data[1]) {
//				case 92:
//					plug_closing(p->plug,
//							"Proxy error: SOCKS server wanted IDENTD on client",
//							PROXY_ERROR_GENERAL, 0);
//					break;
//				case 93:
//					plug_closing(
//							p->plug,
//							"Proxy error: Username and IDENTD on client don't agree",
//							PROXY_ERROR_GENERAL, 0);
//					break;
//				case 91:
//				default:
//					plug_closing(p->plug,
//							"Proxy error: Error while communicating with proxy",
//							PROXY_ERROR_GENERAL, 0);
//					break;
//				}
//
//				return 1;
//			}
//			bufchain_consume(&p->pending_input_data, 8);
//
//			/* we're done */
//			proxy_activate(p);
//			/* proxy activate will have dealt with
//			 * whatever is left of the buffer */
//			return 1;
//		}
//	}
//
//	plug_closing(p->plug, "Proxy error: unexpected proxy error",
//			PROXY_ERROR_UNEXPECTED, 0);
//	return 1;
//}

/* SOCKS version 5 */
//int proxy_socks5_negotiate(Proxy_Socket p, int change) {
//	if (p->state == PROXY_CHANGE_NEW) {
//
//		/* initial command:
//		 *  version number (1 byte) = 5
//		 *  number of available authentication methods (1 byte)
//		 *  available authentication methods (1 byte * previous value)
//		 *    authentication methods:
//		 *     0x00 = no authentication
//		 *     0x01 = GSSAPI
//		 *     0x02 = username/password
//		 *     0x03 = CHAP
//		 */
//
//		char command[5];
//		int len;
//
//		command[0] = 5; /* version 5 */
//		if (p->cfg.proxy_username[0] || p->cfg.proxy_password[0]) {
//			command[2] = 0x00; /* no authentication */
//			len = 3;
//			proxy_socks5_offerencryptedauth(command, &len);
//			command[len++] = 0x02; /* username/password */
//			command[1] = len - 2; /* Number of methods supported */
//		} else {
//			command[1] = 1; /* one methods supported: */
//			command[2] = 0x00; /* no authentication */
//			len = 3;
//		}
//
//		sk_write(p->sub_socket, command, len);
//
//		p->state = 1;
//		return 0;
//	}
//
//	if (change == PROXY_CHANGE_CLOSING) {
//		/* if our proxy negotiation process involves closing and opening
//		 * new sockets, then we would want to intercept this closing
//		 * callback when we were expecting it. if we aren't anticipating
//		 * a socket close, then some error must have occurred. we'll
//		 * just pass those errors up to the backend.
//		 */
//		return plug_closing(p->plug, p->closing_error_msg,
//				p->closing_error_code, p->closing_calling_back);
//	}
//
//	if (change == PROXY_CHANGE_SENT) {
//		/* some (or all) of what we wrote to the proxy was sent.
//		 * we don't do anything new, however, until we receive the
//		 * proxy's response. we might want to set a timer so we can
//		 * timeout the proxy negotiation after a while...
//		 */
//		return 0;
//	}
//
//	if (change == PROXY_CHANGE_ACCEPTING) {
//		/* we should _never_ see this, as we are using our socket to
//		 * connect to a proxy, not accepting inbound connections.
//		 * what should we do? close the socket with an appropriate
//		 * error message?
//		 */
//		return plug_accepting(p->plug, p->accepting_sock);
//	}
//
//	if (change == PROXY_CHANGE_RECEIVE) {
//		/* we have received data from the underlying socket, which
//		 * we'll need to parse, process, and respond to appropriately.
//		 */
//
//		if (p->state == 1) {
//
//			/* initial response:
//			 *  version number (1 byte) = 5
//			 *  authentication method (1 byte)
//			 *    authentication methods:
//			 *     0x00 = no authentication
//			 *     0x01 = GSSAPI
//			 *     0x02 = username/password
//			 *     0x03 = CHAP
//			 *     0xff = no acceptable methods
//			 */
//			char data[2];
//
//			if (bufchain_size(&p->pending_input_data) < 2)
//				return 1; /* not got anything yet */
//
//			/* get the response */
//			bufchain_fetch(&p->pending_input_data, data, 2);
//
//			if (data[0] != 5) {
//				plug_closing(p->plug,
//						"Proxy error: SOCKS proxy returned unexpected version",
//						PROXY_ERROR_GENERAL, 0);
//				return 1;
//			}
//
//			if (data[1] == 0x00)
//				p->state = 2; /* no authentication needed */
//			else if (data[1] == 0x01)
//				p->state = 4; /* GSSAPI authentication */
//			else if (data[1] == 0x02)
//				p->state = 5; /* username/password authentication */
//			else if (data[1] == 0x03)
//				p->state = 6; /* CHAP authentication */
//			else {
//				plug_closing(
//						p->plug,
//						"Proxy error: SOCKS proxy did not accept our authentication",
//						PROXY_ERROR_GENERAL, 0);
//				return 1;
//			}
//			bufchain_consume(&p->pending_input_data, 2);
//		}
//
//		if (p->state == 7) {
//
//			/* password authentication reply format:
//			 *  version number (1 bytes) = 1
//			 *  reply code (1 byte)
//			 *    0 = succeeded
//			 *    >0 = failed
//			 */
//			char data[2];
//
//			if (bufchain_size(&p->pending_input_data) < 2)
//				return 1; /* not got anything yet */
//
//			/* get the response */
//			bufchain_fetch(&p->pending_input_data, data, 2);
//
//			if (data[0] != 1) {
//				plug_closing(p->plug, "Proxy error: SOCKS password "
//						"subnegotiation contained wrong version number",
//						PROXY_ERROR_GENERAL, 0);
//				return 1;
//			}
//
//			if (data[1] != 0) {
//
//				plug_closing(p->plug, "Proxy error: SOCKS proxy refused"
//						" password authentication", PROXY_ERROR_GENERAL, 0);
//				return 1;
//			}
//
//			bufchain_consume(&p->pending_input_data, 2);
//			p->state = 2; /* now proceed as authenticated */
//		}
//
//		if (p->state == 8) {
//			int ret;
//			ret = proxy_socks5_handlechap(p);
//			if (ret)
//				return ret;
//		}
//
//		if (p->state == 2) {
//
//			/* request format:
//			 *  version number (1 byte) = 5
//			 *  command code (1 byte)
//			 *    1 = CONNECT
//			 *    2 = BIND
//			 *    3 = UDP ASSOCIATE
//			 *  reserved (1 byte) = 0x00
//			 *  address type (1 byte)
//			 *    1 = IPv4
//			 *    3 = domainname (first byte has length, no terminating null)
//			 *    4 = IPv6
//			 *  dest. address (variable)
//			 *  dest. port (2 bytes) [network order]
//			 */
//
//			char command[512];
//			int len;
//			int type;
//
//			type = sk_addrtype(p->remote_addr);
//			if (type == ADDRTYPE_IPV4) {
//				len = 10; /* 4 hdr + 4 addr + 2 trailer */
//				command[3] = 1; /* IPv4 */
//				sk_addrcopy(p->remote_addr, command + 4);
//			} else if (type == ADDRTYPE_IPV6) {
//				len = 22; /* 4 hdr + 16 addr + 2 trailer */
//				command[3] = 4; /* IPv6 */
//				sk_addrcopy(p->remote_addr, command + 4);
//			} else {
//				assert(type == ADDRTYPE_NAME);
//				command[3] = 3;
//				sk_getaddr(p->remote_addr, command + 5, 256);
//				command[4] = strlen(command + 5);
//				len = 7 + command[4]; /* 4 hdr, 1 len, N addr, 2 trailer */
//			}
//
//			command[0] = 5; /* version 5 */
//			command[1] = 1; /* CONNECT command */
//			command[2] = 0x00;
//
//			/* port */
//			command[len - 2] = (char) (p->remote_port >> 8) & 0xff;
//			command[len - 1] = (char) p->remote_port & 0xff;
//
//			sk_write(p->sub_socket, command, len);
//
//			p->state = 3;
//			return 1;
//		}
//
//		if (p->state == 3) {
//
//			/* reply format:
//			 *  version number (1 bytes) = 5
//			 *  reply code (1 byte)
//			 *    0 = succeeded
//			 *    1 = general SOCKS server failure
//			 *    2 = connection not allowed by ruleset
//			 *    3 = network unreachable
//			 *    4 = host unreachable
//			 *    5 = connection refused
//			 *    6 = TTL expired
//			 *    7 = command not supported
//			 *    8 = address type not supported
//			 * reserved (1 byte) = x00
//			 * address type (1 byte)
//			 *    1 = IPv4
//			 *    3 = domainname (first byte has length, no terminating null)
//			 *    4 = IPv6
//			 * server bound address (variable)
//			 * server bound port (2 bytes) [network order]
//			 */
//			char data[5];
//			int len;
//
//			/* First 5 bytes of packet are enough to tell its length. */
//			if (bufchain_size(&p->pending_input_data) < 5)
//				return 1; /* not got anything yet */
//
//			/* get the response */
//			bufchain_fetch(&p->pending_input_data, data, 5);
//
//			if (data[0] != 5) {
//				plug_closing(
//						p->plug,
//						"Proxy error: SOCKS proxy returned wrong version number",
//						PROXY_ERROR_GENERAL, 0);
//				return 1;
//			}
//
//			if (data[1] != 0) {
//				char buf[256];
//
//				strcpy(buf, "Proxy error: ");
//
//				switch (data[1]) {
//				case 1:
//					strcat(buf, "General SOCKS server failure");
//					break;
//				case 2:
//					strcat(buf, "Connection not allowed by ruleset");
//					break;
//				case 3:
//					strcat(buf, "Network unreachable");
//					break;
//				case 4:
//					strcat(buf, "Host unreachable");
//					break;
//				case 5:
//					strcat(buf, "Connection refused");
//					break;
//				case 6:
//					strcat(buf, "TTL expired");
//					break;
//				case 7:
//					strcat(buf, "Command not supported");
//					break;
//				case 8:
//					strcat(buf, "Address type not supported");
//					break;
//				default:
//					sprintf(buf + strlen(buf),
//							"Unrecognised SOCKS error code %d", data[1]);
//					break;
//				}
//				plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
//
//				return 1;
//			}
//
//			/*
//			 * Eat the rest of the reply packet.
//			 */
//			len = 6; /* first 4 bytes, last 2 */
//			switch (data[3]) {
//			case 1:
//				len += 4;
//				break; /* IPv4 address */
//			case 4:
//				len += 16;
//				break;/* IPv6 address */
//			case 3:
//				len += (unsigned char) data[4];
//				break; /* domain name */
//			default:
//				plug_closing(p->plug, "Proxy error: SOCKS proxy returned "
//						"unrecognised address format", PROXY_ERROR_GENERAL, 0);
//				return 1;
//			}
//			if (bufchain_size(&p->pending_input_data) < len)
//				return 1; /* not got whole reply yet */
//			bufchain_consume(&p->pending_input_data, len);
//
//			/* we're done */
//			proxy_activate(p);
//			return 1;
//		}
//
//		if (p->state == 4) {
//			/* TODO: Handle GSSAPI authentication */
//			plug_closing(p->plug,
//					"Proxy error: We don't support GSSAPI authentication",
//					PROXY_ERROR_GENERAL, 0);
//			return 1;
//		}
//
//		if (p->state == 5) {
//			if (p->cfg.proxy_username[0] || p->cfg.proxy_password[0]) {
//				char userpwbuf[514];
//				int ulen, plen;
//				ulen = strlen(p->cfg.proxy_username);
//				if (ulen > 255)
//					ulen = 255;
//				if (ulen < 1)
//					ulen = 1;
//				plen = strlen(p->cfg.proxy_password);
//				if (plen > 255)
//					plen = 255;
//				if (plen < 1)
//					plen = 1;
//				userpwbuf[0] = 1; /* version number of subnegotiation */
//				userpwbuf[1] = ulen;
//				memcpy(userpwbuf + 2, p->cfg.proxy_username, ulen);
//				userpwbuf[ulen + 2] = plen;
//				memcpy(userpwbuf + ulen + 3, p->cfg.proxy_password, plen);
//				sk_write(p->sub_socket, userpwbuf, ulen + plen + 3);
//				p->state = 7;
//			} else
//				plug_closing(p->plug, "Proxy error: Server chose "
//						"username/password authentication but we "
//						"didn't offer it!", PROXY_ERROR_GENERAL, 0);
//			return 1;
//		}
//
//		if (p->state == 6) {
//			int ret;
//			ret = proxy_socks5_selectchap(p);
//			if (ret)
//				return ret;
//		}
//
//	}
//
//	plug_closing(p->plug, "Proxy error: Unexpected proxy error",
//			PROXY_ERROR_UNEXPECTED, 0);
//	return 1;
//}

/* ----------------------------------------------------------------------
 * `Telnet' proxy type.
 *
 * (This is for ad-hoc proxies where you connect to the proxy's
 * telnet port and send a command such as `connect host port'. The
 * command is configurable, since this proxy type is typically not
 * standardised or at all well-defined.)
 */

//char *format_telnet_command(SockAddr addr, int port, const Config *cfg) {
//	char *ret = NULL;
//	int retlen = 0, retsize = 0;
//	int so = 0, eo = 0;
//#define ENSURE(n) do { \
//    if (retsize < retlen + n) { \
//	retsize = retlen + n + 512; \
//	ret = sresize(ret, retsize, char); \
//    } \
//} while (0)
//
//	/* we need to escape \\, \%, \r, \n, \t, \x??, \0???,
//	 * %%, %host, %port, %user, and %pass
//	 */
//
//	while (cfg->proxy_telnet_command[eo] != 0) {
//
//		/* scan forward until we hit end-of-line,
//		 * or an escape character (\ or %) */
//		while (cfg->proxy_telnet_command[eo] != 0
//				&& cfg->proxy_telnet_command[eo] != '%'
//				&& cfg->proxy_telnet_command[eo] != '\\')
//			eo++;
//
//		/* if we hit eol, break out of our escaping loop */
//		if (cfg->proxy_telnet_command[eo] == 0)
//			break;
//
//		/* if there was any unescaped text before the escape
//		 * character, send that now */
//		if (eo != so) {
//			ENSURE(eo - so);
//			memcpy(ret + retlen, cfg->proxy_telnet_command + so, eo - so);
//			retlen += eo - so;
//		}
//
//		so = eo++;
//
//		/* if the escape character was the last character of
//		 * the line, we'll just stop and send it. */
//		if (cfg->proxy_telnet_command[eo] == 0)
//			break;
//
//		if (cfg->proxy_telnet_command[so] == '\\') {
//
//			/* we recognize \\, \%, \r, \n, \t, \x??.
//			 * anything else, we just send unescaped (including the \).
//			 */
//
//			switch (cfg->proxy_telnet_command[eo]) {
//
//			case '\\':
//				ENSURE(1);
//				ret[retlen++] = '\\';
//				eo++;
//				break;
//
//			case '%':
//				ENSURE(1);
//				ret[retlen++] = '%';
//				eo++;
//				break;
//
//			case 'r':
//				ENSURE(1);
//				ret[retlen++] = '\r';
//				eo++;
//				break;
//
//			case 'n':
//				ENSURE(1);
//				ret[retlen++] = '\n';
//				eo++;
//				break;
//
//			case 't':
//				ENSURE(1);
//				ret[retlen++] = '\t';
//				eo++;
//				break;
//
//			case 'x':
//			case 'X': {
//				/* escaped hexadecimal value (ie. \xff) */
//				unsigned char v = 0;
//				int i = 0;
//
//				for (;;) {
//					eo++;
//					if (cfg->proxy_telnet_command[eo] >= '0'
//							&& cfg->proxy_telnet_command[eo] <= '9')
//						v += cfg->proxy_telnet_command[eo] - '0';
//					else if (cfg->proxy_telnet_command[eo] >= 'a'
//							&& cfg->proxy_telnet_command[eo] <= 'f')
//						v += cfg->proxy_telnet_command[eo] - 'a' + 10;
//					else if (cfg->proxy_telnet_command[eo] >= 'A'
//							&& cfg->proxy_telnet_command[eo] <= 'F')
//						v += cfg->proxy_telnet_command[eo] - 'A' + 10;
//					else {
//						/* non hex character, so we abort and just
//						 * send the whole thing unescaped (including \x)
//						 */
//						ENSURE(1);
//						ret[retlen++] = '\\';
//						eo = so + 1;
//						break;
//					}
//
//					/* we only extract two hex characters */
//					if (i == 1) {
//						ENSURE(1);
//						ret[retlen++] = v;
//						eo++;
//						break;
//					}
//
//					i++;
//					v <<= 4;
//				}
//			}
//				break;
//
//			default:
//				ENSURE(2);
//				memcpy(ret + retlen, cfg->proxy_telnet_command + so, 2);
//				retlen += 2;
//				eo++;
//				break;
//			}
//		} else {
//
//			/* % escape. we recognize %%, %host, %port, %user, %pass.
//			 * %proxyhost, %proxyport. Anything else we just send
//			 * unescaped (including the %).
//			 */
//
//			if (cfg->proxy_telnet_command[eo] == '%') {
//				ENSURE(1);
//				ret[retlen++] = '%';
//				eo++;
//			} else if (strnicmp(cfg->proxy_telnet_command + eo, "host", 4)
//					== 0) {
//				char dest[512];
//				int destlen;
//				sk_getaddr(addr, dest, lenof(dest));
//				destlen = strlen(dest);
//				ENSURE(destlen);
//				memcpy(ret + retlen, dest, destlen);
//				retlen += destlen;
//				eo += 4;
//			} else if (strnicmp(cfg->proxy_telnet_command + eo, "port", 4)
//					== 0) {
//				char portstr[8], portlen;
//				portlen = sprintf(portstr, "%i", port);
//				ENSURE(portlen);
//				memcpy(ret + retlen, portstr, portlen);
//				retlen += portlen;
//				eo += 4;
//			} else if (strnicmp(cfg->proxy_telnet_command + eo, "user", 4)
//					== 0) {
//				int userlen = strlen(cfg->proxy_username);
//				ENSURE(userlen);
//				memcpy(ret + retlen, cfg->proxy_username, userlen);
//				retlen += userlen;
//				eo += 4;
//			} else if (strnicmp(cfg->proxy_telnet_command + eo, "pass", 4)
//					== 0) {
//				int passlen = strlen(cfg->proxy_password);
//				ENSURE(passlen);
//				memcpy(ret + retlen, cfg->proxy_password, passlen);
//				retlen += passlen;
//				eo += 4;
//			} else if (strnicmp(cfg->proxy_telnet_command + eo, "proxyhost", 9)
//					== 0) {
//				int phlen = strlen(cfg->proxy_host);
//				ENSURE(phlen);
//				memcpy(ret + retlen, cfg->proxy_host, phlen);
//				retlen += phlen;
//				eo += 9;
//			} else if (strnicmp(cfg->proxy_telnet_command + eo, "proxyport", 9)
//					== 0) {
//				char pport[50];
//				int pplen;
//				sprintf(pport, "%d", cfg->proxy_port);
//				pplen = strlen(pport);
//				ENSURE(pplen);
//				memcpy(ret + retlen, pport, pplen);
//				retlen += pplen;
//				eo += 9;
//			} else {
//				/* we don't escape this, so send the % now, and
//				 * don't advance eo, so that we'll consider the
//				 * text immediately following the % as unescaped.
//				 */
//				ENSURE(1);
//				ret[retlen++] = '%';
//			}
//		}
//
//		/* resume scanning for additional escapes after this one. */
//		so = eo;
//	}
//
//	/* if there is any unescaped text at the end of the line, send it */
//	if (eo != so) {
//		ENSURE(eo - so);
//		memcpy(ret + retlen, cfg->proxy_telnet_command + so, eo - so);
//		retlen += eo - so;
//	}
//
//	ENSURE(1);
//	ret[retlen] = '\0';
//	return ret;
//
//#undef ENSURE
//}

//int proxy_telnet_negotiate(Proxy_Socket p, int change) {
//	if (p->state == PROXY_CHANGE_NEW) {
//		char *formatted_cmd;
//
//		formatted_cmd = format_telnet_command(p->remote_addr, p->remote_port,
//				&p->cfg);
//
//		sk_write(p->sub_socket, formatted_cmd, strlen(formatted_cmd));
//		sfree(formatted_cmd);
//
//		p->state = 1;
//		return 0;
//	}
//
//	if (change == PROXY_CHANGE_CLOSING) {
//		/* if our proxy negotiation process involves closing and opening
//		 * new sockets, then we would want to intercept this closing
//		 * callback when we were expecting it. if we aren't anticipating
//		 * a socket close, then some error must have occurred. we'll
//		 * just pass those errors up to the backend.
//		 */
//		return plug_closing(p->plug, p->closing_error_msg,
//				p->closing_error_code, p->closing_calling_back);
//	}
//
//	if (change == PROXY_CHANGE_SENT) {
//		/* some (or all) of what we wrote to the proxy was sent.
//		 * we don't do anything new, however, until we receive the
//		 * proxy's response. we might want to set a timer so we can
//		 * timeout the proxy negotiation after a while...
//		 */
//		return 0;
//	}
//
//	if (change == PROXY_CHANGE_ACCEPTING) {
//		/* we should _never_ see this, as we are using our socket to
//		 * connect to a proxy, not accepting inbound connections.
//		 * what should we do? close the socket with an appropriate
//		 * error message?
//		 */
//		return plug_accepting(p->plug, p->accepting_sock);
//	}
//
//	if (change == PROXY_CHANGE_RECEIVE) {
//		/* we have received data from the underlying socket, which
//		 * we'll need to parse, process, and respond to appropriately.
//		 */
//
//		/* we're done */
//		proxy_activate(p);
//		/* proxy activate will have dealt with
//		 * whatever is left of the buffer */
//		return 1;
//	}
//
//	plug_closing(p->plug, "Proxy error: Unexpected proxy error",
//			PROXY_ERROR_UNEXPECTED, 0);
//	return 1;
//}
